Data generation device, data output device, encoding device and decoding device

Abstract

To realize backward compatibility.SOLUTION: A data generation device generates a video elementary stream with a second luminance dynamic range wider than a first luminance dynamic range, the video elementary stream having reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range but supports reproduction of video having the first luminance dynamic range. The video elementary stream includes: VUI for storing first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video elementary stream; and SEI for storing second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video elementary stream.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a data generating method, a data reproducing method, a data generating device, and a data reproducing device. [Background technology]

[0002] Non-Patent Documents 1 to 3 disclose techniques for generating, encoding, and multiplexing video. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] ITU-T H.265 “High efficiency video coding”, October 2014 [Non-Patent Document 2] Recommendation ITU-R BT.709-5(04 / 2002) "Parameter values ​​for the HDTV standards for production and international program exchange" [Non-Patent Document 3] Recommendation ITU-R BT.2020-1(06 / 2014) “Parameter values ​​for ultra-high definition television systems for production and international program exchange” Summary of the Invention [Problem to be solved by the invention]

[0004] New methods for generating such video data are constantly being devised, but it is desirable to be able to achieve backward compatibility with conventional devices.

[0005] Therefore, an object of the present invention is to provide a data generation method, a data reproduction method, a data generation device, or a data reproduction device that can achieve backward compatibility. [Means for solving the problem]

[0006] In order to achieve the above object, a data generating device according to one aspect of the present invention is a data generating device for generating a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, the video elementary stream being compatible for playback in a first device that does not support playback of videos in the second luminance dynamic range and supports playback of videos in the first luminance dynamic range, the data generating device including: an encoding unit that generates the video elementary stream by performing encoding in compliance with a video encoding standard, the video elementary stream including: video usability information (VUI) storing first transfer function information for identifying a first OETF referenced by the first device when the first device decodes the video elementary stream; and supplemental enhancement information (SEI) storing second transfer function information for identifying a second OETF referenced by the second device when a second device that supports playback of videos in the second luminance dynamic range decodes the video elementary stream, the first luminance dynamic range being SDR (Standard Dynamic Range), and the second luminance dynamic range being HDR (High Dynamic Range). The first OETF and the second OETF are functions that convert a luminance value into a code value, and the VUI is included in an SPS (Sequence Parameter Set).

[0007] Furthermore, these general or specific aspects may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0008] The present invention can provide a data generation method, a data reproduction method, a data generation device, or a data reproduction device that can achieve backward compatibility. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration of a system according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of an OETF according to an embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a configuration of a VUI according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of an OETF according to an embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of an extension of the OETF according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of a configuration of an SEI message according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of a configuration of an SEI message according to the embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of a configuration of an SPS according to an embodiment. [Figure 9] FIG. 9 is a diagram illustrating an example of a configuration of a hybrid descriptor according to the embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of a configuration of a hybrid descriptor according to the embodiment. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of an HEVC descriptor according to an embodiment. [Figure 12] FIG. 12 is a diagram showing the operation of the stream and data playback device according to the embodiment. [Figure 13] FIG. 13 is a flowchart showing the operation of the data generating device according to the embodiment. [Figure 14] FIG. 14 is a flowchart showing the operation of the data reproducing device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Findings on which the present invention is based) HDR (High Dynamic Range) is attracting attention as a method that supports a luminance range with an expanded maximum luminance value in order to express bright light such as specular reflections that cannot be expressed with current TV signals in a more realistic brightness while maintaining the dark gradation of conventional images. Specifically, the luminance range method supported by conventional TV signals is called SDR (Standard Dynamic Range), which has a maximum luminance value of 100 nits, whereas HDR is expected to expand the maximum luminance value to over 1000 nits.

[0011] On the other hand, it is desirable to be able to play such HDR-compatible video data on playback devices that are only compatible with the conventional SDR. In other words, there is a demand for video data that allows HDR video to be played on HDR-compatible playback devices, and SDR video to be played on SDR-compatible playback devices.

[0012] A data generation method according to one embodiment of the present invention is a data generation method for generating video data having a second luminance dynamic range wider than a first luminance dynamic range, the video data being compatible for playback in a first device that does not support playback of video in the second luminance dynamic range and supports playback of video in the first luminance dynamic range, the data generation method including the steps of: generating a video signal included in the video data using a second OETF (Opto-Electrical Transfer Function) referenced by the second device when the second device supports playback of video in the second luminance dynamic range decodes the video data; storing first transfer function information for identifying the first OETF referenced by the first device when the first device decodes the video data in VUI (Video Usability Information) within the video data; and storing the second transfer function information for identifying the second OETF in SEI (Supplemental enhancement information) within the video data.

[0013] According to this, in a device that supports only the reproduction of video in the first luminance dynamic range, the video data can be reproduced using the first transfer function information, and in a device that supports the reproduction of video in the second luminance dynamic range, the video data can be reproduced using the second function information. In this way, the data generation method can generate video data that is backward compatible.

[0014] For example, the data generation method may further include storing hybrid information indicating whether the video data is video data of the second luminance dynamic range in a descriptor of a multiplexing layer.

[0015] According to this, in a data playback device that plays back video data, preparations for switching the playback method can be made in advance by using the hybrid information in the multiplex layer, which allows the data playback device to smoothly switch the playback method.

[0016] For example, the first OETF may be an OETF defined in linear terms of the luminance of the video data in a first range of the luminance of the video data, and defined in power terms of the luminance of the video data in a second range larger than the first range.

[0017] For example, the second OETF may be an OETF that is defined in linear terms of the luminance of the video data in a third range of the luminance of the video data, defined in power terms of the luminance of the video data in a fourth range larger than the third range, and defined in logarithmic terms of the luminance of the video data in a fifth range larger than the fourth range.

[0018] For example, the first OETF may be an OETF defined in terms of powers of the luminance of the video data.

[0019] For example, the second OETF may be an OETF defined in power terms of the luminance of the video data in a sixth range of the luminance of the video data, and defined in logarithmic terms of the luminance of the video data in a seventh range greater than the sixth range.

[0020] For example, the first OETF may be an OETF defined in BT.709 or BT.2020, and the second OETF may be a hybrid gamma OETF.

[0021] For example, the data generating method may further include storing dynamic range increase information indicating a difference between a luminance dynamic range of the video data and the first luminance dynamic range in the SEI.

[0022] For example, the data generating method may further include a step of storing picture maximum average level information indicating a maximum average luminance value among the average luminance values ​​of all pictures included in the video sequence in the SEI.

[0023] Moreover, a data reproduction method according to one embodiment of the present invention is a data reproduction method for reproducing video data having a second luminance dynamic range wider than a first luminance dynamic range, the video data being compatible for reproduction in a first device that does not support reproduction of video in the second luminance dynamic range but supports reproduction of video in the first luminance dynamic range, the video data including: a VUI (Video Usability Information) in which first transfer function information for identifying a first OETF (Opto-Electrical Transfer Function) to be referenced by the first device when the first device decodes the video data; and a SEI (Supplemental enhancement information) in which second transfer function information for identifying a second OETF to be referenced by the second device when a second device, which supports reproduction of video in the second luminance dynamic range, decodes the video data, the data reproduction method including a step of acquiring the second transfer function information included in the SEI; and a step of reproducing a video signal included in the video data by referring to the second OETF identified by the acquired second transfer function information.

[0024] According to this, the data playback method can play back video data that has backward compatibility.

[0025] For example, the video data may further include hybrid information stored in a descriptor of a multiplexing layer indicating whether the video data is video data of the second luminance dynamic range, and the data playback method may further include a step of acquiring the hybrid information from the video data, a step of preparing to switch between playback of the first luminance dynamic range and playback of the second luminance dynamic range based on the acquired hybrid information, and a step of switching between playback of the first luminance dynamic range and playback of the second luminance dynamic range at a timing when a video sequence switches.

[0026] According to this, preparations for switching the playback format can be made in advance using the hybrid information in the multiplex layer, which allows the playback format to be switched smoothly.

[0027] For example, the first OETF may be an OETF defined in linear terms of the luminance of the video data in a first range of the luminance of the video data, and defined in power terms of the luminance of the video data in a second range larger than the first range.

[0028] For example, the second OETF may be an OETF that is defined in linear terms of the luminance of the video data in a third range of the luminance of the video data, defined in power terms of the luminance of the video data in a fourth range larger than the third range, and defined in logarithmic terms of the luminance of the video data in a fifth range larger than the fourth range.

[0029] For example, the first OETF may be an OETF defined in terms of powers of the luminance of the video data.

[0030] For example, the second OETF may be an OETF defined in power terms of the luminance of the video data in a sixth range of the luminance of the video data, and defined in logarithmic terms of the luminance of the video data in a seventh range greater than the sixth range.

[0031] For example, the first OETF may be an OETF defined in BT.709 or BT.2020, and the second OETF may be a hybrid gamma OETF.

[0032] For example, the data reproduction method may further include a step of obtaining dynamic range increase information indicating a difference between a luminance dynamic range of the video data and the first luminance dynamic range from the SEI.

[0033] For example, the data reproduction method may further include a step of obtaining picture maximum average level information indicating a maximum average luminance value among the average luminance values ​​of all pictures included in the video sequence from the SEI.

[0034] In addition, a data generating device according to one embodiment of the present invention is a data generating device that generates video data having a second luminance dynamic range wider than a first luminance dynamic range, the video data being compatible for playback in a first device that does not support playback of video in the second luminance dynamic range and supports playback of video in the first luminance dynamic range, and includes a generation unit that generates a video signal included in the video data using a second OETF (Opto-Electrical Transfer Function) referenced by the second device when the second device supports playback of video in the second luminance dynamic range decodes the video data, a first storage unit that stores first transfer function information for identifying the first OETF referenced by the first device when the first device decodes the video data in VUI (Video Usability Information) within the video data, and a second storage unit that stores the second transfer function information for identifying the second OETF in SEI (Supplemental enhancement information) within the video data.

[0035] According to this, in a device that supports only the reproduction of video in the first luminance dynamic range, the video data can be reproduced using the first transfer function information, and in a device that supports the reproduction of video in the second luminance dynamic range, the video data can be reproduced using the second transfer function information. In this way, the data generating device can generate video data that is backward compatible.

[0036] Moreover, a data playback device according to one embodiment of the present invention is a data playback device that plays video data having a second luminance dynamic range wider than a first luminance dynamic range, the video data being compatible with playback in a first device that does not support playback of video in the second luminance dynamic range but supports playback of video in the first luminance dynamic range, the video data including: VUI (Video Usability Information) storing first transfer function information for identifying a first OETF (Opto-Electrical Transfer Function) to be referenced by the first device when the first device decodes the video data; and SEI (Supplemental enhancement information) storing second transfer function information for identifying a second OETF to be referenced by the second device when a second device that supports playback of video in the second luminance dynamic range decodes the video data, the data playback device including: an acquisition unit that acquires the second transfer function information included in the SEI; and a playback unit that reproduces a video signal included in the video data by referring to the second OETF identified by the acquired second transfer function information.

[0037] This allows the data playback device to play back video data that is backward compatible.

[0038] These comprehensive or specific aspects may be realized as a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0039] Hereinafter, the embodiment will be specifically described with reference to the drawings.

[0040] Note that the embodiments described below each show a specific example of the present invention. The numerical values, shapes, materials, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components that are not described in an independent claim showing a superordinate concept are described as optional components.

[0041] In addition, detailed explanations of terminology, data structure, processing contents, etc. may be omitted below, but specific examples of these are similar to the contents described in Non-Patent Documents 1, 2, and 3.

[0042] First, the configuration of a system according to the present embodiment will be described. Fig. 1 is a block diagram showing the configuration of a system according to the present embodiment. The system shown in Fig. 1 includes a data generating device 110 and a data reproducing device 120.

[0043] Data generating device 110 generates video data having a second luminance dynamic range (e.g., HDR) that is wider than a first luminance dynamic range (e.g., SDR), the video data being compatible with playback on a first device that does not support playback of video in the second luminance dynamic range but does support playback of video in the first luminance dynamic range.

[0044] The data generating device 110 includes a video signal generating unit 111 , an encoding unit 112 , and a multiplexing unit 113 .

[0045] The video signal generating unit 111 converts the luminance value of the original image corresponding to HDR into a code value using an OETF (Opto-Electrical Transfer Function). Here, the OETF is a function for converting the luminance value of the original image into a code value, as shown in FIG. 2. Specifically, the video signal generating unit 111 uses an OETF for HDR compatible with SDR. This will be described in detail later.

[0046] The encoding unit 112 generates a video elementary stream by performing encoding on the obtained code values ​​in accordance with a video encoding standard such as HEVC. The multiplexing unit 113 generates a transport stream (e.g., a DVB transport stream) by multiplexing the video elementary stream.

[0047] The generated transport stream is transmitted to the data reproduction device 120, for example, by broadcast waves. Note that, although an example in which broadcast waves are used is described here, transmission via a network or the like may also be possible, or transmission via a recording medium such as a BD disc may also be possible.

[0048] The data reproduction device 120 reproduces the video data generated by the data generation device 110. The data reproduction device 120 includes a demultiplexing unit 121, a decoding unit 122, and a reproduction unit 123.

[0049] The demultiplexer 121 generates a video elementary stream by demultiplexing the video data (transport stream). The decoder 122 generates a code value by decoding the obtained video elementary stream in accordance with a video encoding standard such as HEVC.

[0050] The reproduction unit 123 restores the image by converting the obtained code value into a luminance value using an EOTF (Electro-Optical Transfer Function) corresponding to the above OETF. Here, the EOTF is an inverse function of the OETF and is a function for converting the code value into a luminance value. The obtained image is displayed on a display unit or the like included in the data reproduction device 120 or connected to the data reproduction device 120.

[0051] The signaling of the transfer function (OETF) of this embodiment will be described below.

[0052] The transfer function is signaled using transfer_characteristics in Video Usability Information (VUI) included in Sequence Parameter Set (SPS) in the HEVC and AVC video coding standards.

[0053] Also, only the OETF is signaled, not the EOTF.

[0054] Figure 3 is a diagram showing the syntax of the VUI parameters. As shown in Figure 3, the VUI includes first transfer function information (transfer_characteristics). Figure 4 is a table showing the meaning of transfer_characteristics. Values ​​1 and 14 are assigned to the OETF of SDR supported by DVB (Digital Video Broadcasting) UHD (Ultra HD) Phase 1 receivers.

[0055] As described in Non-Patent Document 1 and the like, transfer_characteristics indicates the opto-electrical transfer characteristic of the original image.

[0056] Note that signaling means that a signal for identifying desired information or a signal indicating the desired information itself is included in a transmission signal so that the receiving side can obtain the desired information. For example, in the examples of Figures 3 and 4, transfer_characteristics for identifying the OETF is included in the transmission signal, and the receiving side identifies the OETF based on the received transfer_characteristics.

[0057] An example of an extension for the new OETF according to this embodiment will now be described.

[0058] In the HEVC and AVC standards, a reserved value is provided for further extension. Therefore, this reserved value can be assigned to an SDR-compatible HDR OETF (hereinafter, referred to as a hybrid OETF). For example, as shown in FIG. 5, the hybrid OETF is assigned to the reserved values ​​18 to 20.

[0059] However, in this case, data reproduction devices (receivers) with old specifications that do not support HDR cannot recognize this new value and recognize it as a backup value. This causes a problem that backward compatibility cannot be achieved when a new value is used in the hybrid OETF. Here, the hybrid OETF is an OETF that includes a part expressed in powers of luminance and a part expressed in logarithms of luminance, such as the BBC Hybrid Gamma OETF.

[0060] In this embodiment, the value of the first transfer function information (transfer_characteristics) is set to 1 (BT.709) or 14 (BT.2020) like conventional SDR.

[0061] In addition, second transfer function information (HDR_transfer_characteristic) is signaled separately from the first transfer function information to specify the hybrid OETF. This allows a data reproduction device that does not support HDR to specify the OETF for SDR using the first transfer function information (transfer_characteristics), and a data reproduction device that supports HDR to specify the OETF for HDR using the second transfer function information.

[0062] Here, the second transfer function information (HDR_transfer_characteristic) is used for signaling the OETF for HDR. Specifically, the OETF for HDR is compatible with the OETF for SDR specified by the first transfer function information (transfer_characteristics).

[0063] For example, the second transfer function information (HDR_transfer_characteristic) indicates one of the three hybrid OETFs shown in Fig. 5. The second transfer function information may be information indicating whether or not a hybrid OETF is used. The number of selectable hybrid OETFs may be any number, as long as it is 1 or more.

[0064] In addition, the hybrid OETF has characteristics that are approximately the same as those of the SDR OETF in the low luminance range, as shown in Fig. 2. In other words, when a video signal generated using the hybrid OETF is reproduced using the hybrid OETF, the reproduced luminance is approximately the same in the low luminance range when the video signal is reproduced using the hybrid OETF and when the video signal is reproduced using the SDR OETF. This reduces the difference in luminance value between when the video signal is reproduced using an HDR device and when the video signal is reproduced using an SDR device, so that a video with little discomfort can be reproduced even when the video signal is reproduced using the SDR OETF.

[0065] A number of methods for storing the second transfer function information will be described below. These methods are roughly divided into a method for storing the second transfer function information in a video coding layer and a method for storing the second transfer function information in a multiplexing layer.

[0066] First, a method for storing the second transfer function information in the video coding layer will be described.

[0067] Fig. 6 is a diagram showing the syntax of an HDR hybrid gamma SEI message (hereinafter, referred to as a hybrid SEI message) according to the present embodiment. As shown in Fig. 6, the hybrid SEI message includes second transfer function information (HDR_transfer_characteristic).

[0068] A hybrid SEI message is only present in an IRAP NAL unit or an I-picture and is valid for the rest of the coded video sequence.

[0069] In addition, the hybrid SEI message may be a prefix or suffix SEI message.

[0070] Also, in the application standardization document, the presence of this SEI message may be made mandatory when HDR_transfer_characteristic is a predetermined fixed value.

[0071] Also, as shown in FIG. 7, the hybrid SEI message may include dynamic range increase information (dynamic_range_increase) and picture maximum average level information (maximum_average_picture_level) in addition to or instead of the second transfer function information.

[0072] The dynamic range increase information (dynamic_range_increase) is used to calculate the coefficient k and takes only the values ​​of 0, 1, or 2. The coefficient k indicates the difference from the dynamic range of SDR and is calculated by the following (Equation 1). Specifically, the coefficient k indicates the magnification of the dynamic range of the video to the dynamic range of SDR.

[0073] k = 2 × dynamic_range_increase + 4 (Eq. 1)

[0074] The picture maximum average level information (maximum_average_picture_level) indicates the maximum average picture level of all pictures included in the video sequence, where the average picture level is the average value of pixel luminance expressed as a percentage of the maximum luminance.

[0075] In this way, by using the dynamic range increase information and the picture maximum average level information, the difference from SDR can be set to any range.

[0076] Also, in application standardization documents, the presence of this SEI message may be mandatory where k is a predefined fixed value, for example k=4 for DVB and k=8 for BDA.

[0077] Fig. 8 is a diagram showing the structure of an extended SPS. As shown in Fig. 8, dynamic range increase information (dynamic_range_increase) and picture maximum average level information (maximum_average_picture_level) may be included in the SPS.

[0078] Next, a method for storing the second transfer function information in the multiplexing layer will be described.

[0079] FIG. 9 is a diagram showing the configuration of a hybrid descriptor (HDR_hybrid_gamma_descriptor) which is a new descriptor at the MPEG2-TS level according to this embodiment.

[0080] As shown in FIG. 9, the hybrid descriptor includes a hybrid OETF flag (HDR_hybrid_gamma_OETF_flag) and second transfer function information (HDR_transfer_characteristic).

[0081] The hybrid OETF flag (HDR_hybrid_gamma_OETF_flag) indicates whether the content is HDR-encoded using hybrid OETF. For example, when the hybrid OETF flag is 1, the content is HDR-encoded using hybrid OETF.

[0082] It should be noted that the hybrid OETF flag is not necessarily required, and only the second transfer function information may be used.

[0083] In addition, the hybrid descriptor is stored in at least one of the PMT (Program Map Table) defined by MPEG, the SDT (Service Description Table) defined by DVB in the DVB-SI standard, and the EIT (Event Information Table) defined by DVB in the DVB-SI standard.

[0084] The PMT indicates the PID of a TS packet that stores an image or audio, etc. A data playback device can extract the TS packet of the desired image or audio by obtaining the PID of the desired image or audio, etc. from the PMT.

[0085] The SDT indicates the name of the channel (service), the type of EIT transmitted on each channel, digital copy control information, and the like.

[0086] The EIT indicates information related to a program, such as the name of the program, the broadcast date and time, and the broadcast content.

[0087] If the PMT includes a hybrid descriptor, the hybrid descriptor is assigned only to the video elementary stream. In this case, however, it is necessary for the broadcasting station to control the modification of the PMT, and this modification may be difficult.

[0088] When the SDT contains a hybrid descriptor, the contents of the hybrid descriptor are not updated frequently. Therefore, it is preferable to apply the contents of the hybrid descriptor to the entire service.

[0089] When the EIT contains a hybrid descriptor, there is an advantage that the contents of the hybrid descriptor can be changed on an event-by-event basis.

[0090] Fig. 10 is a diagram showing another configuration of the hybrid descriptor according to the present embodiment. As shown in Fig. 10, the hybrid descriptor may include dynamic range increase information (dynamic_range_increase) and picture maximum average level information (maximum_average_picture_level) in addition to or instead of the second transfer function information.

[0091] FIG. 11 is a diagram showing the configuration of an HEVC descriptor (HEVC_descriptor) according to this embodiment. The HEVC descriptor is an MPEG2-TS level descriptor. As shown in FIG. 11, a reserved value (reserved) of the HEVC descriptor is replaced with a hybrid coding flag (hdr_hybrid_gamma_coded_content_flag) and dynamic range increase information (dynamic_range_increase). Note that the hybrid coding flag is a flag similar to the above-mentioned hybrid OETF flag (HDR_hybrid_gamma_OETF_flag). In addition, the above-mentioned other information (second transfer function information and picture maximum average level information) may be included in the HEVC descriptor.

[0092] A similar extension may also be made to the AVC descriptor (AVC_video_descriptor).

[0093] Furthermore, the above-mentioned hybrid descriptor (HDR_hybrid_gamma_descriptor) may be combined with the signaling of the OETF to the video elementary stream (hybrid SEI message), which allows smooth parameter switching in the data playback device.

[0094] This operation will be described in detail below. Figure 12 shows the structure of a stream and the operation of a data playback device.

[0095] The hybrid descriptor (HDR_hybrid_gamma_descriptor) including the hybrid OETF flag (HDR_hybrid_gamma_OETF_flag) starts to be transmitted shortly before the actual change. Upon receiving this hybrid OETF flag, the data reproduction device prepares for the change between SDR and HDR.

[0096] To make the parameter change effective, an End Of Sequence (EOS) indicating the end of a video sequence is inserted into the video elementary stream. A Random Access Point (RAP) following the EOS may or may not contain a hybrid SEI message adapted to the hybrid descriptor signaled immediately before.

[0097] The data playback device detects whether EOS and hybrid SEI messages are present and makes changes accordingly.

[0098] In the example shown in FIG. 12, the data playback device acquires a hybrid descriptor including HDR_hybrid_gamma_OETF_flag=0 while performing HDR operation. This causes the data playback device to start preparations for switching operation from HDR to SDR. Next, the data playback device switches from HDR to SDR when it acquires EOS. Also, there is no hybrid SEI message in the SDR video elementary stream, and the data playback device does not acquire the hybrid SEI message.

[0099] Next, the data playback device acquires a hybrid descriptor including HDR_hybrid_gamma_OETF_flag=1 while performing SDR operation. This causes the data playback device to start preparations for switching operation from SDR to HDR. Next, the data playback device switches from SDR to HDR when it acquires EOS.

[0100] The operations of the data generating device 110 and the data reproducing device 120 based on the above will now be described.

[0101] 13 is a flowchart of the operation of data generating device 110 according to the present embodiment. Data generating device 110 generates video data that is HDR video data and is compatible with playback on a first device that does not support HDR video playback and supports SDR video playback.

[0102] First, the video signal generating unit 111 generates a video signal by converting the luminance value of the original image into a code value using the second OETF (S101). Next, the encoding unit 112 generates a video elementary stream by encoding the video signal. At this time, the encoding unit 112 stores, in the VUI in the video data (video elementary stream), first transfer function information for identifying the first OETF referenced by the first device that supports only SDR when the first device plays back the video data. In addition, the encoding unit 112 stores, in the SEI in the video data, second transfer function information for identifying the second OETF referenced by the second device that supports HDR when the second device decodes the video data (S102).

[0103] Here, the VUI and SEI belong to the video coding layer. The first OETF is, for example, an OETF defined in BT.709 or BT.2020, and the second OETF is, for example, a BBC Hybrid Gamma OETF.

[0104] Furthermore, the encoding unit 112 may further store in the SEI dynamic range increase information indicating a difference between the luminance dynamic range of the video data and the luminance dynamic range of the SDR. Furthermore, the encoding unit 112 may further store in the SEI picture maximum average level information indicating the maximum average luminance value among the average luminance values ​​of all the pictures included in the video sequence.

[0105] Next, the multiplexing unit 113 generates a transport stream by multiplexing the video elementary stream data. At this time, the multiplexing unit 113 stores hybrid information (hybrid OETF flag) indicating whether the video data is HDR video data or not in the hybrid descriptor of the multiplex layer (S103).

[0106] In the example shown in Figure 12, the hybrid descriptor includes at least a hybrid OETF flag, but the hybrid descriptor may further include second transfer function information, dynamic range increase information, or picture maximum average level information.

[0107] Similarly, the hybrid SEI message may include at least one of a hybrid OETF flag, second transfer function information, dynamic range increase information, and picture maximum average level information.

[0108] In addition, in the above description, the hybrid OETF flag and the second transfer function information are described as separate information, but the second transfer function information may be used instead of the hybrid OETF flag. That is, the hybrid OETF flag does not need to be used. For example, depending on whether the second transfer function information is included in the video data, it is possible to signal whether the video data is HDR video data (whether the hybrid OETF is used). Alternatively, depending on whether the second transfer function information indicates the hybrid OETF or the SDR OETF, it may be possible to signal whether the video data is HDR video data.

[0109] In the above description, an example in which the hybrid OETF is indicated by the second transfer function information has been described, but as shown in FIG. 12, when HDR images and SDR images are mixed in the video data, the second transfer function information may indicate the OETF of SDR even for the SDR images. This allows a data reproduction device that supports HDR to always refer to the second transfer function information regardless of whether the video data is SDR or HDR. In other words, the data reproduction device does not need to refer to the first transfer function information. This can simplify the processing of the data reproduction device.

[0110] 14 is a flowchart of the operation of the data reproduction device 120 according to the present embodiment. The data reproduction device 120 reproduces video data that is HDR video data and is compatible with reproduction on a first device that does not support HDR video reproduction and supports SDR video reproduction. Here, this video data is, for example, video data generated by the data generation device 110.

[0111] First, the demultiplexer 121 generates a video elementary stream by demultiplexing the video data (transport stream). At this time, the demultiplexer 121 acquires hybrid information (e.g., a hybrid OETF flag) from a hybrid descriptor of the video data (S121). Note that the demultiplexer 121 may further acquire at least one of dynamic range increase information and picture maximum average level information from the hybrid descriptor.

[0112] Next, data reproduction device 120 prepares to switch between SDR reproduction and HDR reproduction based on the acquired hybrid information (S122).

[0113] Next, the decoding unit 122 generates a video signal (code value) by decoding the video elementary stream. If the immediately preceding hybrid OETF flag indicates that the hybrid OETF is used, the decoding unit 122 acquires second transfer function information included in the hybrid SEI in the video elementary stream (S123). Note that the decoding unit 122 may further acquire at least one of dynamic range increase information and picture maximum average level information from the hybrid SEI.

[0114] The reproduction unit 123 reproduces the video signal included in the video data by referring to the second OETF specified by the acquired second transfer function information (S124). Furthermore, the reproduction unit 123 switches between SDR reproduction and HDR reproduction at the timing when the video sequence switches. Specifically, the reproduction unit 123 reproduces the data after EOS in the changed format. Furthermore, when dynamic range increase information or picture maximum average level information is acquired, reproduction is performed using this information.

[0115] If the immediately preceding hybrid OETF flag indicates that the hybrid OETF is not used, in step S123, the decoding unit 122 acquires first transfer function information included in the VUI in the video elementary stream. In step S124, the reproduction unit 123 reproduces the video signal included in the video data by referring to the second OETF specified by the acquired first transfer function information. As described above, if the second transfer function information selectively indicates the first OETF or the second OETF, the decoding unit 122 may always acquire the second transfer function information, and the reproduction unit 123 may refer to the first OETF or the second OETF indicated by the second transfer function information.

[0116] As described above, in the present embodiment, in addition to the first transfer function information stored in the VUI, the second transfer function information is stored in the SEI message. This makes it possible to realize HDR encoding using a hybrid OETF such as a BBC Hybrid Gamma OETF.

[0117] Specifically, a descriptor can be used to signal to the multiplexing layer whether the content is HDR coded with hybrid OETF.

[0118] In addition, the combination of the new SEI message and the new descriptor enables smooth switching between HDR and SDR by a data playback device.

[0119] Moreover, the first OETF may be a function defined by the following (Equation 2).

[0120]

number

[0121] Here, L is the luminance of the image, which is normalized to 0≦L≦1 as the reference white level, V is a value corresponding to the electrical signal, and α, β, γ, δ, and ρ are constants, with specific numerical examples being α=4.5, β=0.018, γ=1.099, δ=0.45, and ρ=0.099.

[0122] In other words, as shown in (Equation 2), the first OETF may be an OETF that is defined in linear terms of the luminance of the video data in a first range of the luminance of the video data, and that is defined in power terms of the luminance of the video data in a second range larger than the first range.

[0123] Furthermore, the first OETF may be a function expressed by the following (Equation 3).

[0124]

number

[0125] Here, L is the luminance of the image, normalized as 0≦L≦1. E is a value corresponding to the normalized voltage of the reference white level, which is proportional to the absolute light intensity detected in the reference camera color channel RGB. As a result, E' is a nonlinear signal. α, β, γ, and δ are constants, and specific numerical examples are α=4.5, β=0.018 (for 10-bit system) or 0.0181 (for 12-bit system), γ=1.099 (for 10-bit system) or 1.0993 (for 12-bit system), δ=0.45, and ρ=0.099.

[0126] The second OETF may be a function defined by the following (Equation 4), in which the conversion function is defined in logarithmic terms at high luminance.

[0127]

number

[0128] Here, L is the luminance of the image, normalized by the reference white level. However, L can be greater than 1. That is, this conversion function supports luminance greater than the reference white. V is a value corresponding to the electrical signal. μ is the breakpoint between the gamma curve and the logarithmic curve, and determines the maximum value of L when V is less than or equal to 1. Also, α, β, γ, δ, and ρ are certain constants, and specific numerical examples are α=4.5, β=0.018, γ=1.099, δ=0.45, and ρ=0.099.

[0129] In other words, as shown in (Equation 4), the second OETF may be an OETF that is defined in linear terms of the luminance of the video data in a third range of the luminance of the video data, defined in power terms of the luminance of the video data in a fourth range larger than the third range, and defined in logarithmic terms of the luminance of the video data in a fifth range larger than the fourth range.

[0130] Moreover, the first OETF may be a function defined by the following (Equation 5).

[0131]

number

[0132] Here, L is the luminance of the image, which is normalized as 0≦L≦1 as the reference white level, V is a value corresponding to the electrical signal, and α is a constant, and a specific example value is α=0.5.

[0133] That is, as shown in (Equation 5), the first OETF may be an OETF defined in terms of powers of the luminance of the video data.

[0134] Moreover, the second OETF may be a function defined by the following (Equation 6): In this OETF, the conversion function is defined in logarithmic terms at high luminance.

[0135]

number

[0136] Moreover, α is a certain constant, and a specific numerical example is α=0.5.

[0137] In other words, as shown in (Equation 6), the second OETF may be an OETF that is defined in power terms of the luminance of the video data in a sixth range of the luminance of the video data, and that is defined in logarithmic terms of the luminance of the video data in a seventh range that is larger than the sixth range.

[0138] Although the data generating device (data generating method) and the data reproducing device (data reproducing method) according to one or more aspects have been described based on the embodiments, the present invention is not limited to these embodiments. As long as it does not deviate from the gist of the present invention, various modifications conceived by those skilled in the art to the present embodiments and forms constructed by combining components in different embodiments may also be included within the scope of one or more aspects.

[0139] For example, in each of the above embodiments, each component may be implemented by dedicated hardware such as a circuit, or by executing a software program suitable for each component. Each component may be implemented by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. [Industrial Applicability]

[0140] The present invention can be applied to a data transmission device or a data reproduction device such as a BD device. [Explanation of symbols]

[0141] 110 Data Generator 111 Video signal generator 112 Encoding section 113 Multiplexer 120 Data playback device 121 Demultiplexer 122 Decoding section 123 Playback Department

Claims

1. 1. A data generating device that generates a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, the video elementary stream being compatible for playback in a first device that does not support playback of video images having the second luminance dynamic range and supports playback of video images having the first luminance dynamic range, An encoding unit that generates the video elementary stream by performing encoding in accordance with a video encoding standard, The video elementary stream includes: A VUI (Video Usability Information) storing first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) referred to by the first device when the first device decodes the video elementary stream; and a supplemental enhancement information (SEI) storing second transfer function information for specifying a second OETF to be referenced by a second device when the second device, which is compatible with playback of the image in the second luminance dynamic range, decodes the video elementary stream; The first luminance dynamic range is a standard dynamic range (SDR), and the second luminance dynamic range is a high dynamic range (HDR), The first OETF and the second OETF are functions for converting a luminance value into a code value, The VUI is included in the SPS (Sequence Parameter Set). Data generation device.

2. 2. A data output device for transmitting the video elementary stream according to claim 1 via broadcast waves or a network.

3. 1. An encoding device that generates a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, the video elementary stream being compatible for playback on a first device that does not support playback of video having the second luminance dynamic range and supports playback of video having the first luminance dynamic range, An encoding unit that generates the video elementary stream by performing encoding in accordance with a video encoding standard, The encoding unit generates a VUI (Video Usability Information) and a SEI (Supplemental enhancement information) in the video elementary stream, The encoding unit stores in the VUI first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) to be referred to by the first device when the first device decodes the video elementary stream; The encoding unit stores, in the SEI, second transfer function information for specifying a second OETF to be referenced by a second device when the second device, which supports playback of the image in the second luminance dynamic range, decodes the video elementary stream; The first luminance dynamic range is a standard dynamic range (SDR), and the second luminance dynamic range is a high dynamic range (HDR), The first OETF and the second OETF are functions for converting a luminance value into a code value, The VUI is included in the SPS (Sequence Parameter Set). Encoding device.

4. 1. A decoding device that decodes a video elementary stream having a second luminance dynamic range wider than a first luminance dynamic range, the video elementary stream being compatible for playback on a first device that does not support playback of video having the second luminance dynamic range and supports playback of video having the first luminance dynamic range, A decoding unit that decodes the video elementary stream by performing decoding in accordance with a video encoding standard, The video elementary stream includes: A VUI (Video Usability Information) storing first transfer function information for specifying a first OETF (Opto-Electrical Transfer Function) referred to by the first device when the first device decodes the video elementary stream; and a supplemental enhancement information (SEI) storing second transfer function information for specifying a second OETF to be referenced by a second device when the second device, which is compatible with playback of the image in the second luminance dynamic range, decodes the video elementary stream; The first luminance dynamic range is a standard dynamic range (SDR), and the second luminance dynamic range is a high dynamic range (HDR), The first OETF and the second OETF are functions for converting a luminance value into a code value, The VUI is included in the SPS (Sequence Parameter Set). Decryption device.

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